1 in 4 unresponsive patients with brain injury have a “hidden” consciousness

THURSDAY, Aug. 15, 2024 (HealthDay News) — Some comatose patients with severe brain injuries may pay closer attention to their surroundings than previously thought, a new study suggests.

The researchers found that about one in four patients responds covertly to instructions: their brain shows activity even when their body is not moving.

When the coma patients were asked to imagine opening and closing their hand, they showed brain activity that suggested they repeatedly followed this instruction, as shown by MRI and EEG brain scans.

This shows that some patients with severe brain injuries pay attention to their environment, said lead researcher Yelena Bodien, a researcher at the Center for Neurotechnology and Neurorecovery at Massachusetts General Hospital.

“These findings raise critical ethical, clinical and scientific questions – such as how can we harness this previously unrecognized cognitive capacity to build a communication system and promote continued recovery?” Bodien said in a hospital press release.

For the study, researchers examined 241 people with a brain injury who showed no outward signs of consciousness, such as the ability to respond to simple instructions.

The study included data from participants at six different sites in the United States, the United Kingdom and Europe, collected over a period of approximately 15 years.

All patients had suffered severe brain injuries, often from a stroke, cardiac arrest or a traumatic event such as a car accident.

MRI and EEG brain scans showed that 60% of the subjects (25%) actually tried to respond to these instructions but had no control over their bodies.

This phenomenon is called cognitive motor dissociation, researchers say. Patients understand language, remember instructions and can maintain attention, but the connection between their thinking and their motor skills is broken.

Knowing that a person is conscious, even if they can't show it, can influence the care they receive, Bodien said.

“Families have told us that when a positive test result showing cognitive motor dissociation is shared with the patient's clinical team, the way the team interacts with the loved one can change,” Bodien said. “Suddenly the team is paying more attention to subtle behavioral cues that can be controlled voluntarily, or talking to the patient or playing music in the room.”

“On the other hand, failure to recognize cognitive motor dissociation can have serious consequences, including premature withdrawal of life support, missing signs of consciousness, and lack of access to intensive rehabilitation,” Bodien added.

Now that doctors know that some patients are conscious but unable to respond, “I think we now have an ethical obligation to engage with these patients and try to help them connect with the world,” said lead researcher Dr. Nicholas Schiff, a professor of neurology and neuroscience at the Feil Family Brain and Mind Research Institute at Weill Cornell Medicine in New York City.

One possible solution could be the brain-computer interfaces currently being tested to help paralyzed or “locked down” patients regain their ability to communicate, the researchers say.

The study was published on August 14 in New England Journal of Medicine.

More information

Johns Hopkins Medicine offers more information on traumatic brain injury.

SOURCE: Massachusetts General Hospital, press release, August 14, 2024